3IO jeffeky: the mollusca of western Sussex. 



cristata, which var. I have found however at Ratham 



and also at Wisbro' Green. 

 Planorbis albus. Common. 

 P. spirorbis. Common. 

 P. vortex. Less common than the last. 

 P. complanatus. Common. 

 P. corneus. Have found this species in the levels of the Arun 



near Pulborough and Burpham, also at Bersted near 



Bognor, but it does not occur in the Chichester district 



nor west of it that I can ascertain. 



p. contortus. Not so common as some other species of this 

 genus. 



Physa hypnorum. Rather alocal species: frequenting stagnant 



ditches, which dry up in summer. This snail then 



buries itself in the mud at the bottom, and does not 



appear to turn out again when the ditches get filled in 



the autumn; so that its enjoyment of life must be 



confined to a very short period, and I have often 



been led to wonder how it continues to exist under 



such circumstances. Occasionally it may be found in 



slow running waters, which do not entirely dry up in 



summer. 



It is probably the most rapid traveller of all our 

 aquatic snails, and does not well bear the confinement 

 of an aquarium, being almost sure to crawl out before it 

 has been many days in one, especially if the water be 

 allowed to attain anything beyond a cool temperature. 



As one of the lung-breathers (Pulmonobranchiata) 

 it has to come to the surface of the water periodically 

 for a supply of air. When in deep water (though it 

 naturally prefers shallow, and loves to crawl, foot 

 upwards, on the surface) it will frequently spin a web of 



J.C, Hi., April, 1882 



